[mythtv] [PATCH] viavld interlaced patch

Terry Barnaby terry1 at beam.ltd.uk
Tue Oct 5 09:26:39 UTC 2004


Robert Clark wrote:
> On Sun, 2004-10-03 at 06:55, Terry Barnaby wrote:
> 
> 
>>Robert Clark wrote:
> 
> 
>>> I've had another look at this and I am now seeing evidence of
>>>interlacing (flickering when paused during motion). Bizarrely, this is
>>>only happening some of the time, though, so I think it's not 100%
>>>correct yet.
> 
> 
>>> One thing which you've probably already checked is scaling. I had
>>>great difficulty convincing MythTV not to scale the image and any
>>>vertical scaling destroys the interlacing. Eventually I gave up and
>>>patched it to hardcode the display aspect to match the source.
> 
> 
>>One thing on this, what is your MythTv setup ?
> 
> 
>   I'm using Fedora Core 2 with kernel 2.6.8 with the epia2 drm kernel
> patch (drm version 1.3.0), Xorg 6.7.0 with Unichrome driver r25 &
> libviaXvMC 0.11.3 and MythTV CVS from 2004-09-24.
> 
>   On top of these I've added patches to get the new drm to compile with
> the FC2 kernel, disable the hardware flicker filter, the qmatrix and
> jitter fixes for MythTV you posted on the Unichrome mailing list and a
> patch to fix the aspect ratio.
> 
>   I'm running X with a 720x576 50Hz modeline, TV output only, PAL
> format, S-Video out & overscan. Via (VLD) hardware acceleration is
> enabled in Myth, deinterlacing is not.
> 
> 
>>I presume you are using a PAL/NTSC TV as an output device ?
> 
> 
>   Yes.
> 
> 
>>If you are using, as I am, a Via M10000 box that includes the VT1622
>>TV output chip (or similar),
> 
> 
>   I have an MEII6000 with the VT1622A TV encoder.
> 
> 
>>this has a "de-flicker" option which is enabled
>>by default in the Unichrome Via X driver. 
> 
> 
>>For watching Video I have turned it off with a hard hack (patch enclosed).
> 
> 
>   Thanks, your patch is better than mine (it actually has comments) :)
> 
>   This should probably be made an X driver option at some point, I
> guess?
> 
> 
>>What is your video source to get the interlaced pictures ?
> 
> 
>   I'm using two video sources for testing at the moment. One is a region
> 2 PAL DVD (Father Ted) which I can play back through Unichrome patched
> MPlayer. This looks fine from the point of view of interlacing, so it's
> a good reference for comparing Myth's output to. The other is a DVB
> recording imported into Myth (I don't have my DVB card yet). I can also
> play this nuv file back through MPlayer for a closer comparison of the
> interlacing behaviour.
> 
>   Have you tried MPlayer at all? To my untrained eye the output looks
> perfect. The only problem is the lack of sync-to-vbl means the sync
> drifts and, eventually, the fields get displayed in the wrong order.
> Probably not that difficult to fix for someone who knew what they were
> doing.
> 
> 	Robert
> 
> 
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> 
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Hi Robert,

Seems a very similar set up to mine :)

The de-flicker filter option would be best controlled via the program
driving the display as you may want it when displaying web pages for example.
It could possibly be done by vialibXvMC, which would normally only be used when
outputing video, but an XServer call would be better perhaps as an Xv option.

I hav'nt tried Mplayer as yet, hav'nt found the time ! I will have a go.
Also, at the moment I believe the TVOUT chip on my setup may be scaling the
image. I would be interested in you xorg.conf mode lines and your patch
to hardcode the display aspect to match the source.

Terry

-- 
Dr Terry Barnaby                     BEAM Ltd
Phone: +44 1454 324512               Northavon Business Center, Dean Rd
Fax:   +44 1454 313172               Yate, Bristol, BS37 5NH, UK
Email: terry at beam.ltd.uk             Web: www.beam.ltd.uk
BEAM for: Visually Impaired X-Terminals, Parallel Processing, Software
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